Targeting biomarkers in the gas phase through a chemoresistive electronic nose based on graphene functionalized with metal phthalocyanines

Abstract

An electronic nose based on graphene chemiresistor sensors functionalized with phthalocyanines has been developed to detect selected biomarkers in the gas phase for breathomics, environmental monitoring, and food control applications.

A Chemiresistor Sensor Array Based on Graphene Nanostructures: From the Detection of Ammonia and Possible Interfering VOCs to Chemometric Analysis

“…Considering the space generated by PC1 and PC2 ( Figure 5 a), as well as the space created by PC1 and PC3 ( Figure 5 b), all the tested gas molecules are clearly discriminated, since no overlap among different target gas clusters is observed. Furthermore, as previously found for arrays based on carbon nanomaterials [ 41 , 49 ], a concentration trend is established in each cluster, i.e., each gas concentration decreases going towards the center of the reference system, as indicated by the arrows in Figure 5 . It is worth mentioning that although the developed sensors do not show a particular high response to all gases but ammonia, when their response is combined in the PCA analysis, the whole array is able to completely discriminate each gas contribution.…”

“…As often reported in literature [ 17 , 18 , 41 ] and already mentioned in the introduction, a way to overcome the selectivity problem for single chemiresistor sensors is to deal with an array coupled with chemometric analysis on the whole dataset collected with all chemiresistor sensors upon exposure to the selected target gas molecules at different concentrations, i.e., to deal with an electronic nose.…”

“…Carbon nanotubes have been largely studied as single sensors [ 26 , 27 , 28 ] and, even to a lesser extent, also as electronic noses [ 17 , 29 ], while, only in the past few years, graphene, thanks to its high sensitivity to the surface adsorption of gas molecules [ 30 ], its high in-plane conductivity, and its low electrical intrinsic noise [ 31 ], has attracted the interest or researchers working in the sensors field. Although recent studies have clearly demonstrated the possibility to develop highly sensitive graphene sensors after proper functionalization [ 32 , 33 , 34 , 35 , 36 , 37 ], still few are the works exploiting graphene to develop sensors array [ 38 , 39 , 40 ], especially in a chemiresistor configuration [ 41 ].…”

Machine‐Learning‐Aided NO2 Discrimination with an Array of Graphene Chemiresistors Covalently Functionalized by Diazonium Chemistry

“…This agrees with the electron-withdrawing nature of the covalently attached aryl units. [35] The efficiency and effectiveness of the grafting procedure are further supported by the appearance of the D-band in the functionalized layers. This band, located around 1340 cm À 1 , is related to some disorder in the graphene structure, [45] and in particular, in the present case, to the sp 3 hybridization of some graphene C atoms upon the covalent attachment of the aryl radicals.…”

“…[25,[32][33][34]) have been reported so far, while graphene-based e-noses are not widely diffused. [35] Noncovalent functionalization of pristine graphene, [35] was achieved via the drop-casting of solutions of metal phthalocyanine, an approach that offers a quick way to prototyping new sensing layers, but with little control over the extent and homogeneity of the surface functionalization. Indeed, strict control of surface functionalization is required to enhance the sensing capability, and it is necessary to improve the reliability and reproducibility of sample preparation and thus sensing performance.…”